Arrangement for storing wood chips



Jan. 17, 1967 1. USS-ALBIN CROON ETAL 3,293,749

" ARRANGEMENT FOR STORING WOOD CHIPS Filed June 4, 1-965 6 Sheets-Sheet l Jan. 17, 1967 I. ussaALBm CRQON ETAL. 3,293,749 ARRANGEMENT FOR STORING WOOD CHIPS Filed June 4, 1965 6 Sheets-Sheet 2 m 9 WW I. usswwm cmom ETAL 3,298,749

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' IARRANGEMENT'FOR STORING WOOD CHIPS Filed June 4, 1965 e Sheets-Sheet e quently carried away by a pneumatic conveyor.

United States Patent 3,298,749 ARRANGEMENT FOR STGRING W001) CHIPS Ingemar Liss-Albin Croon, Alfredshem, and Anders Assarsson and Olof Edvin Frisk, ()rnskoldsvik, Sweden, assignors to M0 Och Domsjo Aktieholag, Ornskoldsvik, Sweden, a corporation of Sweden Filed June 4, 1965, Scr. No. 461,378 Claims priority, application Sweden, June 30, 1964, 7,968/64 7 Claims. (Cl. 302-56) The present invention relates to the storage of woodchips in piles. The object of the invention is to eliminate disadvantages which have hitherto been connected with such storage.

In cellulose pulp factories, wallboard factories and saw-mills, the wood can be stored as chips .in chip piles. Such storage is used for various reasons in many types of factories. Thus, erg, a sulfate pulp factory may use chip storage as a rational and cheap method of handling its wood, while a sulfite pulp factory also can utilize the chip storage to improve the quality of the wood raw material.

In a chip pile, there will normally occur temperatures considerably above that of the environment on account of chemical and biological processes in the chip pile. Temperatures within the range of 30 to 60 C. are common and still higher temperatures may occur.

In the warm and moist conditions prevailing in a chip pile, the enzymatic hydrolysis of the extractive substances occurs much rapidly than in the normal storage of logs and at the same time, the extractive substances are oxidized by atmospheric oxygen. These processes result in the extractive substances of the wood being modified after a short period of storage in a chip pile, so that they are more easily solubilized in the sulfite pulping process, and a low extract pulp will be obtained. To achieve a similar low extract content in normal storage of logs will require considerably longer periods of storage of the wood starting material.

To build the pile, conventional systems rely on the use of a tractor for levelling the pile, and when the stored material is to be removed from the pile, the tractor will also be used to feed the chips to a central place along one side of the pile, wherefrom the piles are most fre- A pneumatic conveyor is also the most commonly used apparatus for carrying the chips to the pile. The disadvantages of hitherto known systems are high investment .and maintenance costs of the tractor and the cost of paying the tractor driver. It is also very difiicult to control the storage time of the chips, since it will depend completely on the tractor drivers manner of taking out the chips and the possibilities available to him [for taking the chips to carry it away from the pile. A central control of the various conveying devices is not attainable at a reasonable cost. Also, it is very difficult to supply eig. air to the pile to air it or heat it without the conduits interfering with the removal of chips from the pile.

The present invention contemplates a method and an installation for storing chips which removes the disadvantages referred to above. The method of this invention comprises laying the chips along a substantially circular path to form an interrupted ring, to one end of which the chips are supplied and from the other end of which the chips are removed, the location where the chips are supplied to the ring being continuously moved from the resulting chip pile along said circular path and the location where the chips are removed being simultaneously continuously moved substantially the same distance in the same direction along the circular path.

A suitable installation for carrying the method into practice comprises a chip supplying conveyor for feeding chips to the center of a chip storage station formed as a circular path, a chip feeding device horizontally rotatable around the center of the chip storage station and adapted to receive chips from said chip supplying conveyor at the center of the storage station and to arrange them ann-ularly around said center, a chip removing device horizontally rotatable around said center and adapted to remove the stored chips from the ring and to convey them toward the center, and a chip removing conveyor adapted to receive chips from the chip removal device and to convey it away from the storage.

The invention will be described more in detail below with reference to the accompanying drawings, which illustrate an embodiment of the invention.

7 FIGURE 1 shows somewhat diagrammatically a chip pile arranged in accordance with this invention together with the requisite mechanical means.

FIGURE 2 shows a portion of FIGURE 1 on an enlarged scale.

FIGURES 3 to 6 show sections along the lines IIIIII, IVIV, V-V, and VIVI in FIGURE 1.

' The chips are laid along a substantially circular path to form an interrupted ring 1, to one end 2 of which the chips are supplied and from the other end 3 of which the chips are removed. While the annular pile is being built, the location where they are supplied is continuously moved away from the built chip pile along the the circular path, and similarly the location where the chips are removed from the annular pile is simultaneously continuously moved a substantially corresponding distance in the same direction along the circular path. To build up the pile, chips are fed from a pneumatic conveyor system along a conveyor duct 4 in a culvert 5 below the pile to a chip feeding device at the center of the circular path. The conveyor duct 4 continues vertically to be connected to the horizontal chip feeding conduit 7 which is rotatable in a horizontal plane around the joint 6 and also vertically movable. The conduit 7 is connected to a conveyor conduit 8 which is vertically movable and is rotatable around a horizontal axis. The vertical movability of the conduit 7 is desirable because any irregularities in the portion of the circular path situated next to the central feeding device may cause strong stresses in the conduit. The vertical movab-i'lity can be achieved by making the vertical portion of the conduit 7 concentric with and slidable in the joint 6. As a result of the movement of the conduit 8, the cross-section of the pile will in its top portion be shaped as a segment of a circle and its lower portion be shaped as a parallel trapezium.

The conveyor conduits 7 and 8 are carried by a carriage 9 which is movable around the center and is driven, e.g., by an electric motor or an internal combustion engine. The chip removal device which also moves around the center comprises chains 11 equipped with scraper members and running around sprockets 10. Said chains scrape material toward the bottom plane and toward a suction nozzle 12 from which the material is sucked by a fan 13 to a cyclone 14 where it is separated from the air stream and brought through a sluice feeder to a conveyor 18. The above members It), 11, 12, 13, 14 and 15 are provided on a radially movable carriage 16 which in its turn is arranged on a carriage 17 which is movable circumferentially around the center. The conveyor 18 is carried by the carriage 17 and conveys the chips toward the center of the circular path, where it discharges the chips through the hopper 19 to a pneumatic conveyor 20 to be fed to the factory.

The air supplied by the fan 13 is fed through a conduit 21 to electrical heating units 22 disposed on the carriage 9 to be heated, if necessary, and then to be supplied to perforate pipes 23 extending into the pile to heat or air the bottom portion of the chip pile. The perforate pipes 23 are carried by the carriage 9 and accompany it in its circular path.

If the driving means of the carriages are electrical motors, power will be supplied to the carriages from a connecting means 24 arranged at the center of the pile.

In the embodiment described above, pneumatic conveyors have been shown, but other types of conveyors, e.g., conveyor belts, can also be used. Similarly, the chains 11 with their scraper members may be replaced by, e.g., screw conveyors for feeding the chips to the suction nozzle 12. The carriages 9 and 17 can be combined in a single carriage. The feeding device at the center of the circular path can also be formed as a central mast, at the top of which the horizontally rotatable feeding conduit is provided at a height at least equal to the height of the pile.

The advantages of the invention are that the great costs of tractor and tractor-driver can be wholly eliminated, since the pile can be built properly without using a tractor. Also, all the chips removed from the removing end will have substantially the same storage time, which is of great importance for the final product. Furthermore, the pile and the mechanical equipment can be monitored in a simple manner from a central control room by means of one or more television cameras.

Air or hot air can be supplied to the pile in a very simple manner and without a particular fan unit, since the exhaust air from the removal end can be used for that purpose It is also possible to supply heat through the perforate pipes by some other medium, e.g., steam, which is delivered from a separate apparatus. Since the perforate pipes for injecting air into the pile are arranged to accompany the carriage in its movement around the center, permanently arranged conduits are dispensed with, which might otherwise be a great hindrance, especially to the removal of the chips from the pile.

The size of the annual pile is determined by the rate of supply of chips per unit time and the storage time desired. The rate of supply can amount to 500 m? per hour for chip conveyance, and provided that the chips are conveyed pneumatically, tube diameters of up to 600 mm. may be required. As a normal value of the pressure at the entrance end of the tube, 0.4 kg. per cm. above atmospheric can be mentioned. The annular pile can be built to any desired height, but normal heights are to 20 meters.

We claim:

1. A method of storing wood chips which comprises laying the chips along a substantially circular path to form an interrupted annular chip pile the cross section of which in its upper portion is in the form of a segment of a circle, and in its lower portion is in the form of a trapezoid, and to one end of which the chips are fed and from the other end of which the chips are removed, the said one end being continuously displaced away from the chip pile along said circular path, while feeding the chips thereto, and said other end being simultaneously continuously displaced along said circular path in the same direction and at substantially the same rate by removal of chips from the pile.

2. An installation for storing wood chips, comprising a chip supplying convey-or for supplying chips to the center of a chip storage place in the form of a circular path, a pneumatic chip feeder means vertically movable and rotatable around a horiozntal axis and horizontally rotatable around the center of said chip storage place and adapted to receive chips from said chip supplying conveyor and to discharge them annularly around said center, a chip removal device horizontally rotatable around said center and adapted to remove chips from the ring and feed them toward the center, and a chip discharging conveyor adapted to receive chips from the chip removal device at the center and to convey them away from the storage place.

3. An installation as in claim 2, in which the chip feeder means comprises a horizontally rotatable central feeding member having a first conveying means for carrying the chips from the central feeding member to a point situated above the circle dividing the base of the circular path in two equal parts, and a second conveying means provided at the end of the first conveying means remote from the central feeding member, the second conveying means being vertically movable and rotatable around a horizontal axis, said conveying means being pneumatic and being connected to a pneumatic conveyor duct serving as the chip supplying conveyor.

4. Installation as in claim 3, in which the first conveying means is vertically movable.

5. Installation as in claim 2, in which the chip removal means comprises a central discharge member provided at the center of the circular path for discharging the chips to a pneumatic conveyor, and a peripheral removal member adapted continuously to take off stored chips from the end of the annular pile and carry it to the central discharge member in such a manner that the removal end of the chip pile is substantially vertical.

6. An installation for storing wood chips, comprising, in combination, pneumatic chip conveyor means for supplying chips to the center of a chip storage place in the form of a circular path, chip discharge means vertically movable and rotatable around a horizontal aXis and horizontally rotatable around the center of the chip storage place and in communication with the pneumatic chip conveyor means and adapted to supply chips to one end of the chip pile, vertically movable mechanical chip removal means horizontally rotatable around the center of the chip storage place, and a second pneumatic chip conveyor means in communication with the chip removal means and adapted to receive chips from the chip removal means and to discharge them away from the chip storage place.

7. A method of storing wood chips which comprises laying the chips along a substantially circular path to form an interrupted annular pile the cross section of which in its upper portion is in the form of a segment of a circle, and in its lower portion is in the form of a trapezoid, and to one end of which the chips are fed and from the other end of which the chips first fed are first removed, the end to which the chips are fed being continuously displaced away from the chip pile along the circular path, While feeding the chips thereto, and the other end from which the chips are removed being simultaneously continuously displaced along the circular path in the same direction and at substantially the same rate by removal of chips first fed from the pile, substantially all of the chips being removed from the pile being stored in the pile for a time sufiicient to effect natural chemical and biological processes occurring in the chip pile.

References Cited by the Examiner UNITED STATES PATENTS 668,960 2/1901 Piez et a1 214-10 3,049,244 8/1962 Hansen 21410 3,108,700 10/1963 Swindells et al. 21410 ANDRES H. NIELSEN, Primary Examiner. 

1. A METHOD OF STORING WOOD CHIPS WHICH COMPRISES LAYING THE CHIPS ALONG A SUBSTANTIALLY CIRCULAR PATH TO FORM AN INTERRUPTED ANNULAR CHIP PILE THE CROSS SECTION OF WHICH IN ITS UPPER PORTION IS IN THE FORM OF A SEGMENT OF A CIRCLE, AND IN ITS LOWER PORTION IS IN THE FORM OF A TRAPEZOID, AND TO ONE END OF WHICH THE CHIPS ARE FED AND FROM THE OTHER END OF WHICH THE CHIPS ARE REMOVED, THE SAID ONE END BEING CONTINUOUSLY DISPLACED AWAY FROM THE CHIP PILE ALONG SAID CIRCULAR PATH, WHILE FEEDING THE CHIPS THERETO, AND SAID OTHER END BEING SIMULTANEOUSLY CONTINUOUSLY DISPLACED ALONG SAID CIRCULAR PATH IN THE SAME DIRECTION AND AT SUBSTANTIALLY THE SAME RATE BY REMOVAL OF CHIPS FROM THE PILE. 